The main reasons of paint failure after application on surface are a poor applicator or improper treatment of the surface.
Dilution defect usually occurs when the dilution of the paint is not done as per manufacturers recommendation. There can be a case of over dilution and under dilution, as well as dilution with the incorrect solvent.
Blistering is a defect caused by trapped moisture or gases in paint film (more likely in enamels). It is nothing but bubbles like appearance on paint film.
Blistering could be due to any of the below reasons: 1) Dampness in the wall due to leakage or seepage. 2) Thick deposition of paint or Putty, Plaster/POP is highly absorptive in nature (Uncured) 3) Applying Emulsion paint over distemper.
Prevent blistering with the following steps: 1) Wall should be free from dampness (waterproof the affected area). 2) Apply paint/putty in thin layers only. 3) Allow Plaster/POP to cure properly. 4) Remove distemper completely before applying emulsion paint.
You can repair blistering by smooth sanding the surface, and then repainting it.
Adhesion failure is when a paint fails to adhere to substrate or underlying coats of paint.
The causes for adhesion failures are as follows: 1) Application of paint over oily, greasy or very smooth surface. 2) Application over loose particles like dust or rust. 3) Not sanding previous coat of gloss paint. 4) Application over partially dried coat.
Prevent adhesion failure by: 1) Ensuring proper surface preparation. 2) Using the correct coating specification and follow the advised over coating times.
Repairing adhesion failure depends upon the extent of adhesion failure. Removal of defective areas will be necessary prior to adequate preparation and application of correct coating system to manufacturer’s recommendations.
Bleeding is defect of undercoat staining through the topcoat.
Bleed through is generally a full or partial. Redissolving of the previous coat or an ingredient of a previous coat and can occur when strong solvents are used in the topcoats.
Prevent bleeding by: 1) Using correct coating specification and materials. 2) Using compatible materials. 3) Using appropriate sealer coat if possible.
You can repair bleeding by: 1) Removing stained or contaminated layers. 2) Applying a suitable sealer coat which will prevent the diffusion of soluble coloured material from beneath. It may be possible to apply a sealer coat without the removal of the stained/contaminated layer.
Blooming or blushing is a hazy deposit on the surface of the paint film resembling the bloom on a grape, resulting in a loss of gloss and a dulling of colour.
Bloom or blush are caused when paint film is exposed to condensation or moisture during curing especially at low temperature (common phenomenon with amine cured epoxies). Incorrect solvent blend can also contribute to blooming.
Prevent blooming by applying and curing coating systems under correct environmental conditions, and follow the manufacturer’s recommendations.
Remove bloom with clean cloth or suitable solvent cleaners. If necessary, apply undercoat/topcoat following manufacturer’s recommendations.
Brush marks is a defect where marks of brush remain in the dried paint film. Pronounced brush marks are known as ropiness.
Brush marks are caused by: 1) Viscosity of material may be too high for brush application. 2) Incorrect thinners used. 3) Inadequate mixing or poor application technique. 4) Paint has poor leveling properties. 5) Two-pack paints may have exceeded application pot-life.
Prevent brush marks by: 1) Using brushing grade of paint and apply adequate thickness. 2) Thinning paint to brushing viscosity. 3) Using within pot-life. 4) Using proper brushes.
You can repair brush marks by: 1) Sanding the surface to a smooth finish, and applying paint (after thinning to desired proportion). 2) Use good quality brushes.
Bubbles within a paint film appear as small blisters. These may be intact or broken (to leave a crater). Bubbling can be found in excessively thick paint films, especially if spray applied, and also with roller application. This should not be confused with blistering.
The causes of bubbles or bubbling are: 1) Trapped air/solvent within the coating which is not released before the surface dries. 2) Air entrainment during mixing. 3) High ambient temperature during application. 4) Factory applied coatings where application is by dipping, electrodeposition or roller coating.
Prevent bubbles or bubbling by: 1) Adjusting viscosity with thinners and following data sheet requirements for maximum application temperature through spray application. 2) Using correct mixing equipment to ensure air is not stirred in during mixing. 3) Applying a mist coat. 4) Adding a defoaming agent to emulsion paints.
You can repair bubbles or bubbling depending on extent and severity of bubbling, sanding or removing the offending coat(s) and recoating.
Chalking is a friable, powdery layer on the surface of a paint film. A change of colour or fading is also seen. Chalking rates vary with pigment concentration and choice of binder. Chalking is a known characteristic of certain paints e.g. epoxy paints.
Chalking is caused by the disintegration of the paint binder on exposure to weathering and/or UV light.
You can repair chalking by removing all powdery deposits by wiping, scrubbing, high pressure washing or sanding. Wipe loose material off and apply a chalk resistant topcoat.
Cracking is the splitting of a dry paint film through at least one coat to form visible cracks which may penetrate down to the substrate. Cracking comes in several forms, from minute cracking to severe cracking.
Cracking is cause by generally a stress related failure and can be attributed to surface movement, ageing, absorption and desorption of moisture and general lack of flexibility of the coating. The thicker the paint film, the greater the possibility it will crack.
Prevent cracking by using the correct coating systems, application techniques and dry film thicknesses. Alternatively, use a more flexible coating system.
You can repair cracking by using sand paper to remove all cracked paint. Correctly reapply the coating system, or use a more flexible system and one less prone to cracking.
Efflorescence is a white (powdery) substance on the substrate of concrete, brick, masonry and plaster. The efflorescence, which comes from the migration of salts, can lift the paint from the substrate.
Efflorescence is caused by soluble salts within the substrate. Moisture brings the salts to the surface of the substrate resulting in coating adhesion failure.
Prevent efflorescence by ensuring the surface is moisture free, clean and suitable for application of the coating system. Remove or eliminate the source of moisture.
Peeling is similar to flaking, although peeling tends to be associated with the soft and pliable fresh coatings, which can be pulled away from or spontaneously flake away from the substrate or from between coats, due to loss of adhesion.
Peeling is the reduction in bond strength of the paint film due to contamination or incompatibility of coats.
Prevent peeling by using the correct coating system, and specification applied to clean and uncontaminated surfaces.
You can repair peeling by removing all soft and pliable coating back to a firm edge, or a total removal. You must sand, clean and apply suitable coating system, as per the recommended procedure.
Tackiness is a degree of stickiness remaining in the film. Although beyond the wet and liquid stage, the paint film remains as a tacky and soft surface, and is sometimes only apparent on touching the coating.
There are various reasons why a paint will remain tacky: 1) Over thickness 2) Excessive thinners; 3) Wrong (lack of) curing agent; 4) Low drying/curing temperature; 5) Use of coating beyond pot life or shelf life.
You can prevent tackiness by: 1) Using the correct coating specifications and materials. 2) Ensuring two-pack materials are correctly mixed. 3) Following paint suppliers recommendations.
To repair tackiness, you must remove defective coating by sanding, then clean it and recoat.